Combine all the chicken tikka ingredients together in a large bowl and mix thoroughly so that each piece of chicken is fully coated in the yogurt mixture. Cover with plastic wrap and refrigerate for at least 30 minutes up to 48 hours.
Turn your Instant Pot to the saute setting. (See your manufacturer's guide for detailed instructions on how to use your instant pot.)
Add the vegetable oil, onion, garlic, ginger, turmeric, garam masala, coriander, cumin, and chili powder. Stir and cook for 3 to 5 minutes, until the onion softens.
Add the fire roasted tomatoes, tomato sauce and stir.
Add the chicken to the Instant Pot, including all the yogurt marinade and stir. Close the lid (follow the manufacturer's guide for instructions on how to close the instant pot lid). Set the Instant Pot to the Manual setting and set the timer to 5 minutes.
Once the Instant Pot cycle is complete, wait until the natural release cycle is complete, should take about 10 minutes. Follow the manufacturer's guide for quick release, if in a rush. Carefully unlock and remove the lid from the instant pot.
Add the half and half, salt and butter and give it a good stir. The butter is added to smooth the sauce.
Garnish with cilantro and serve warm over cooked rice with naan or roti.